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Surgical treatment of brain metastases in the central region

J Neurosurg 126:698–707, 2017

Brain metastases are the most frequent intracranial malignant tumor in adults. Surgical intervention for metastases in eloquent areas remains controversial and challenging. Even when metastases are not in ltrating intra- parenchymal tumors, eloquent areas can be affected. Therefore, this study aimed to describe the role of a functional guided approach for the resection of brain metastases in the central region.

METHODS Thirty-three patients (19 men and 14 women) with perirolandic metastases who were treated at the authors’ institution were reviewed. All participants underwent resection using a functional guided approach, which consisted of using intraoperative brain mapping and/or neurophysiological monitoring to aid in the resection, depending on the functionality of the brain parenchyma surrounding each metastasis. Motor and sensory functions were monitored in all patients, and supplementary motor and language area functions were assessed in 5 and 4 patients, respectively. Clinical data were analyzed at presentation, discharge, and the 6-month follow-up.

RESULTS The most frequent presenting symptom was seizure, followed by paresis. Gross-total removal of the metastasis was achieved in 31 patients (93.9%). There were 6 deaths during the follow-up period. After the removal of the metastasis, 6 patients (18.2%) presented with transient neurological worsening, of whom 4 had worsening of motor function impairment and 2 had acquired new sensory disturbances. Total recovery was achieved before the 3rd month of follow-up in all cases. Excluding those patients who died due to the progression of systemic illness, 88.9% of patients had a Karnofsky Performance Scale score greater than 80% at the 6-month follow-up. The mean survival time was 24.4 months after surgery.

CONCLUSIONS The implementation of intraoperative electrical brain stimulation techniques in the resection of central region metastases may improve surgical planning and resection and may spare eloquent areas. This approach also facilitates maximal resection in these and other critical functional areas, thereby helping to avoid new postoperative neurological deficits. Avoiding permanent neurological de cits is critical for a good quality of life, especially in patients with a life expectancy of over a year.

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Hematoma growth after unilateral drainage of bilateral CSDH

J Neurosurg 126:755–759, 2017

Chronic subdural hematoma (CSDH) is a common form of intracranial hemorrhage with a recurrence rate of 9.2%–26.5% after bur hole surgery. Occasionally patients with bilateral CSDH undergo unilateral surgery because the contralateral hematoma is deemed to be asymptomatic, and in some of these patients the contralateral hematoma may subsequently enlarge, requiring additional surgery. The authors investigated the factors related to the growth of these hematomas.

METHODS Ninety-three patients with bilateral CSDH who underwent unilateral bur hole surgery at Aizu Chuo Hospital were included in a retrospective analysis. Findings on preoperative MRI, preoperative thickness of the drained hema-toma, and the influence of antiplatelet or anticoagulant drugs were considered and evaluated in univariate and multivari-ate analyses.

RESULTS The overall growth rate was 19% (18 of 93 hematomas), and a significantly greater percentage of the hematomas that were iso- or hypointense on preoperative T1-weighted imaging showed growth compared with other hematomas (35.4% vs 2.3%, p < 0.001). Multivariate logistic regression analysis showed that findings on preoperative T1-weighted MRI were the sole significant predictor of hematoma growth, and other factors such as antiplatelet or anti-coagulant drug use, patient age, patient sex, thickness of the treated hematoma, and T2-weighted MRI findings were not significantly related to hematoma growth. The adjusted odds ratio for hematoma growth in the T1 isointense/hypointense group relative to the T1 hyperintense group was 25.12 (95% CI 3.89–51.58, p < 0.01).

CONCLUSIONS The findings of preoperative MRI, namely T1-weighted sequences, may be useful in predicting the growth of hematomas that did not undergo bur hole surgery in patients with bilateral CSDH.

 

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Navigation and Robotics in Spinal Surgery: Where Are We Now?

Neurosurgery 80:S86–S99, 2017

Spine surgery has experienced much technological innovation over the past several decades. The field has seen advancements in operative techniques, implants and biologics, and equipment such as computer-assisted navigation and surgical robotics.

With the arrival of real-time image guidance and navigation capabilities along with the computing ability to process and reconstruct these data into an interactive three-dimensional spinal “map”, so too have the applications of surgical robotic technology.

While spinal robotics and navigation represent promising potential for improving modern spinal surgery, it remains paramount to demonstrate its superiority as compared to traditional techniques prior to assimilation of its use amongst surgeons.

The applications for intraoperative navigation and image-guided robotics have expanded to surgical resection of spinal column and intradural tumors, revision procedures on arthrodesed spines, and deformity cases with distorted anatomy.

Additionally, these platforms may mitigate much of the harmful radiation exposure in minimally invasive surgery to which the patient, surgeon, and ancillary operating room staff are subjected. Spine surgery relies upon meticulous fine motor skills to manipulate neural elements and a steady hand while doing so, often exploiting small working corridors utilizing exposures that minimize collateral damage.

Additionally, the procedures may be long and arduous, predisposing the surgeon to both mental and physical fatigue. In light of these characteristics, spine surgery may actually be an ideal candidate for the integration of navigation and robotic-assisted procedures.

With this paper, we aim to critically evaluate the current literature and explore the options available for intraoperative navigation and robotic-assisted spine surgery.

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Foramen magnum meningiomas: surgical results and risks predicting poor outcomes based on a modified classification

J Neurosurg 126:661–676, 2017

This study aimed to evaluate neurological function and progression/recurrence (P/R) outcome of foramen magnum meningioma (FMM) based on a modified classification.

METHODS This study included 185 consecutive patients harboring FMMs (mean age 49.4 years; 124 females). The authors classified the FMMs into 4 types according to the previous classification of Bruneau and George as follows: Type A (n = 49, 26.5%), the dural attachment of the lesion grows below the vertebral artery (VA); Type B (n = 39, 21.1%), the dural attachment of the lesion grows above the VA; Type C1 (n = 84, 45.4%), the VA courses across the lesion with or without VA encasement or large lesions grow both above and below the bilateral VA; and Type C2 (n = 13, 7.0%), Type C1 plus partial/total encasement of the VA and extradural growth.

RESULTS The median preoperative Karnofsky Performance Scale (KPS) score was 80. Gross-total resection (GTR) was achieved in 154 patients (83.2%). Lower cranial nerve morbidity was lowest in Type A lesions (16.3%). Type C2 lesions were inherently larger (p = 0.001), had a greater percentage of ventrolateral location (p = 0.009) and VA encase-ment (p < 0.001), lower GTR rate (p < 0.001), longer surgical duration (p = 0.015), higher morbidity (38.5%), higher P/R rate (30.8%, p = 0.009), and poorer recent KPS score compared with other types. After a mean follow-up duration of 110.3 months, the most recent follow-up data were obtained in 163 patients (88.1%). P/R was observed in 13 patients (7.2%). The median follow-up KPS score was 90. Compared with preoperative status, recent neurological status was improved in 91 (49.2%), stabilized in 76 (41.1%), and worsened in 18 (9.7%) patients. The multivariate Cox proportional hazard regression model demonstrated Type C2 (HR 3.94, 95% CI 1.04–15.0, p = 0.044), nontotal resection (HR 6.30, 95% CI 1.91–20.8, p = 0.003), and pathological mitosis (HR 7.11, 95% CI 1.96–25.8, p = 0.003) as independent adverse predictors for tumor P/R. Multivariate logistic regression analysis identified nontotal resection (OR 4.06, 95% CI 1.16–14.2, p = 0.029) and pathological mitosis (OR 6.29, 95% CI 1.47–27.0, p = 0.013) as independent risks for poor outcome (KPS score < 80).

CONCLUSIONS The modified classification helped to predict surgical outcome and P/R in addition to the position of the lower cranial nerves. Preoperative imaging studies and neurological function should be reviewed carefully to establish an individualized management strategy to improve long-term outcome.

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Causes of poor outcome in patients admitted with good-grade subarachnoid haemorrhage

Acta Neurochir (2017) 159:559–565

Surgical risk in patients with unruptured aneurysms is well known. The relative impact of surgery and natural history of subarachnoid haemorrhage (SAH) on patients in good clinical condition (World Federation of Neurological Surgeons [WFNS] grades 1 and 2) is less well quantified. The aim of this study was to determine causes of poor outcome in patients admitted in good grade SAH.

Methods A retrospective study of prospectively collected data among WFNS-1 and -2 patients: demographics, SAH and aneurysm-related data, surgical complications and outcome as assesed by the Glasgow Outcome Scale (GOS). Causes of poor outcome (GOS 1–3) were determined.

Results During a 7-year period (2009–15), 56 patients with SAH WFNS-1 (39 patients) or WFNS-2 (17 patients) were treated surgically (21 men, 35 women; mean age, 52.4 years). According to the Fisher scale, 19 patients were grade 1 or 2; 37 patients were grade 3 or 4. Most aneurysms were located at anterior communicating (26) or middle cerebral (15) artery.

Altogether, 11 patients (19.6%) achieved GOS 1–3. This was attributed to SAH-related complications in six patients (rebleeding, vasospasm), surgery in four patients (postopera-tive ischaemia in two, haematoma and ventriculitis in one patient each), grand-mal seizure with aspiration in one patient. Age over 60 years (p = 0.017) and presence of hydrocephalus (p < 0.001) were statistically significant predictors of poor GOS; other variables (e.g. sex, Fisher grade, aneurysm size or location, use of temporary clips, intraoperative rupture, vasospasm) were not significant.

Conclusions Patients admitted in good-grade SAH achieve favourable outcome following surgical aneurysm repair in the majority of cases. Negative factors include age over 60 years and presence of hydrocephalus. Aneurysm surgery following good-grade SAH still carries a small but significant risk similar to that shown in large multi-institutional trials.

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Elective ICP monitoring: how long is long enough?

Acta Neurochir (2017) 159:485–490

Intracranial pressure monitoring is commonly undertaken to assess and manage acute patients following head injury. However, ICP monitoring can also be a useful diagnostic tool in the management of CSF dynamics in elective patients. To date, there is little published research to suggest how long these elective patients require ICP monitoring in order to gain an accurate picture of a patient’s ICP dynamics. At the author’s institution, a minimum of 48-h data collection is currently undertaken in patients with a suspected ICP abnormality.

Methods A retrospective audit was undertaken comparing overall median ICP and overall median pulse amplitude data at three time points, 24 h, 48 h and total time analysed (if longer than 48 h). Paired T-test was used to assess if there were statistically significant differences between 24-h versus 48-h monitoring and total duration of monitoring. All patients admitted over a 6-month period for ICPM who met the inclusion/exclusion criteria were included.

Results Eighteen patients met the criteria. Median age was 45.8 years, range 22–83 years, 12 female and 6 male. No complications were experienced as a result of ICPM. Diagnosis included NPH, IIH, suspected shunt malfunction and Chiari malformation. The results demonstrated that there is no statistical difference between 24 h and 48 h or longer for both overall median ICP and pulse amplitude.

Conclusion The results of this study demonstrate that ICP monitoring of elective adult patients using a Spiegelberg intraparenchymal bolt for 24 h gives an accurate picture of a patient’s ICP dynamics compared with longer periods of monitoring.

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Middle cerebral artery aneurysms with intracerebral hematoma—the impact of side and volume on final outcome

Acta Neurochir (2017) 159:543–547

Middle cerebral artery aneurysms (MCA aneu-rysms) belong to the most frequent type of intracranial aneurysms forming an intracerebral hematoma. The consequences of the hematoma—the laterality, the impact of ICH volume and size of the aneurysm with the final outcome of these patients had not been studied in detail in this location, and we focused on the analysis of these factors.

Methods Patients with MCA aneurysms and associated intracerebral hematomas with a volume ≥10 ml were studied; these were treated from January 2006 to December 2015. During this period, more than 700 patients with spontaneous sub-arachnoid hemorrhage were admitted to the Department of Neurosurgery, University Hospital Brno. The data were collected from the subarachnoid hemorrhage database of the unit and from the local hospital registry. All consecutive patients at the treating center were involved in this retrospective study. We collected clinical data such as age, gender, aneurysm lo-cation, preoperative hematoma size, Hunt-Hess grade and type of surgical procedures. We focused on the analysis of the final outcome [Glasgow Outcome Scale (GOS) score] in relation to ICH volume, side of bleeding and finally the relationship between aneurysm size and the volume of ICH.

Results Fifty-eight patients with an MCA aneurysm and ICH were included; the mean age of this series was 59.4 years. Thirty-six patients (62%) had clinical status Hunt-Hess 4–5 on admission. The mean size of the intracerebral hematoma was 47.1 ml (10–133 ml). Most frequently, in 30 patients (52%), the hematoma had bled into the temporal lobe. Fifty three patients were operated on, and 5 were treated conservatively because of their poor condition. Twenty-three patients (40%) had a favorable Glasgow Outcome Scale score, and 35 (60%) had an unfavorable outcome including 20 patients (35%) who died. Of the 53 patients operated on, 20 (38%) underwent decompressive hemicraniectomy (DHC). Patients with an unfavorable outcome had significantly larger hematomas with a median size of 54 ml, whereas those with a favorable outcome had a median size of 26 ml (p = 0.0022). Larger hematomas were found on the right side. The cutoff volume for an unfavorable outcome in ICH was 25 ml. The outcomes were not related to the side of the ICH (p = 0.42), and the aneurysm size did not predetermine the ICH volume (p = 0.3159).

Conclusion Our study confirms the benefit of the active treatment of patients with MCA aneurysms and associated ICH. A significant proportion of these patients achieves a favorable outcome. No association between the side of bleeding and outcome was demonstrated. Hematomas larger than 25 ml have a greater tendency to lead to an unfavorable outcome. The treatment decision-making process should not differ for either side.

 

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Greenstick fracture technique to correct kyphosis

Although posterior decompressive surgery is widely used to treat patients with cervical myelopathy and multilevel ossification of the posterior longitudinal ligament (OPLL), a poor outcome is anticipated if the sagittal alignment is kyphotic (or K-line negative). Accordingly, it is mandatory to perform anterior decompression and fusion in patients with cervical kyphosis. However, it can be difficult to perform anterior surgery because of the high risk of complications. This present report proposes a novel “greenstick fracture technique” to change the K-line from negative to positive in patients with cervical myelopathy, OPLL, and kyphotic deformity.

METHODS Four patients with cervical myelopathy, continuous-type OPLL, and kyphotic sagittal alignment (who were K-line negative) were indicated for surgery. Posterior laminectomy and lateral mass screw insertions using a posterior approach were performed, followed by anterior surgery. Multilevel discectomy and thinning of the OPLL mass by bur drilling was performed, then an intentional greenstick fracture at each disc level was made to convert the cervical K-line from negative to positive. Finally, posterior instrumentation using a rod was carried out to maintain cervical lordosis.

RESULTS MRI showed complete decompression of the cord by posterior migration in all cases, which had been caused by cervical lordosis. Restoration of neurological defects was confirmed at the 1-year follow-up assessment. No specific complications were identified that were associated with this technique.

CONCLUSIONS A greenstick fracture technique may be effective and safe when applied to patients with cervical myelopathy, continuous-type OPLL, and kyphotic deformity (K-line negative). However, further studies with more cases will be required to reveal its generalizability and safety.

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Does MIS Surgery Allow for Shorter Constructs in the Surgical Treatment of Adult Spinal Deformity?

Neurosurgery 80:489–497, 2017

The length of construct can potentially influence perioperative risks in adult spinal deformity (ASD) surgery. A head-to-head comparison between open and minimally invasive surgery (MIS) techniques for treatment of ASD has yet to be performed.

OBJECTIVE: To examine the impact of MIS approaches on construct length and clinical outcomes in comparison to traditional open approaches when treating similar ASD profiles.

METHODS: Two multicenter databases for ASD, 1 involving MIS procedures and the other open procedures, were propensity matched for clinical and radiographic parameters in this observational study. Inclusion criteria were ASD and minimum 2-year follow-up. Independent t-test and chi-square test were used to evaluate and compare outcomes.

RESULTS: A total of 1215 patients were identified, with 84 patients matched in each group. Statistical significance was found for mean levels fused (4.8 for circumferential MIS [cMIS] and 10.1 for open), mean interbody fusion levels (3.6 cMIS and 2.4 open), blood loss (estimated blood loss 488 mL cMIS and 1762 mL open), and hospital length of stay (6.7 days cMIS and 9.7 days open). There was no significant difference in preoperative radiographic parameters or postoperative clinical outcomes (Owestry Disability Index and visual analog scale) between groups. There was a significant difference in postoperative lumbar lordosis (43.3◦ cMIS and 49.8◦ open) and pelvic incidence-lumbar lordosis correction (10.6◦ cMIS and 5.2◦ open) in the open group. There was no significant difference in reoperation rate between the 2 groups.

CONCLUSION: MIS techniques for ASD may reduce construct length, reoperation rates, blood loss, and length of stay without affecting clinical and radiographic outcomes when compared to a similar group of patients treated with open techniques.

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Imaging of Intracranial Pressure Disorders

Neurosurgery 80:341–354, 2017

Intracranial pressure (ICP) is the pressure inside the bony calvarium and can be affected by a variety of processes, such as intracranial masses and edema, obstruction or leakage of cerebrospinal uid, and obstruction of venous out flow. This review focuses on the imaging of 2 important but less well understood ICP disorders: idiopathic intracranial hypertension and spontaneous intracranial hypotension. Both of these ICP disorders have salient imaging findings that are important to recognize to help prevent their misdiagnosis from other common neurological disorders.

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The mononostril endonasal transethmoidal-paraseptal approach

Acta Neurochir (2017) 159:453–457

The use of endoscopes in transnasal surgery offers increased visualization. To minimize rhinological morbidity without restriction in manipulation, we introduced the mononostril transethmoidal-paraseptal approach.

Methods The aim of the transethmoidal-paraseptal approach is to create sufficient space within the nasal cavity, without removal of nasal turbinates and septum. Therefore, as a first step, a partial ethmoidectomy is performed. The middle and superior turbinates are then lateralized into the ethmoidal space, allowing a wide sphenoidotomy with exposure of the central skull base.

Conclusions This minimally invasive transethmoidal-paraseptal approach is a feasible alternative to traumatic transnasal concepts with middle turbinate and extended septal resection.

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An update on idiopathic intracranial hypertension

Acta Neurochir (2017) 159:491–499

Idiopathic intracranial hypertension (IIH) is still a grey area in the knowledge of the aetiology, diagnosis and management of neurosurgical diseases. The definition of IIH has been reviewed over time and many hypotheses have been expressed as cause of the disease. The literature supplies very little evidence-based information to guide our decision-making process when it comes to treat the disease. In this review we sum up the latest information regarding the aetiology and therapy of IIH. Additionally, we make an attempt to unify the diagnostic criteria of Dandy, Friedman and Wall established from 1937 to date.

Method

In this narrative review, we attempt to update the current standpoint to IIH, evaluate the input until now and consider future directions for research. The vast majority of the literature consisted of cohort studies, case control studies, systematic reviews and other narrative reviews.

Results

Pathophysiology: The incidence of IIH is steadily in- creasing. Several pathophysiological theories have been pro- posed in the literature based on the flow of cerebrospinal fluid.

Diagnosis: We attempt to fuse all the three diagnostic ap- proaches published in the literature that detect IIH, while pre- serving the individual characteristics of each approach.

Treatment:

Based on evidence-based trials, the current use of acetazolamide in comparison with placebo or with topiramate has been evaluated. In the interventions’ field, there seems to be a consonance about the alarming symptoms and what the most suitable operation is in each case. There is some disagreement about the indications for venous sinus transversus stenting and its risk/benefit ratio.

Conclusions

Until now there is no class I guideline to which our decision-making can be based on for the management of IIH. A lack of systematic reviews and randomised control trials has been noted. If we focused our research on that, we could develop a standardised treatment protocol.

 

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Consensus guidelines for postoperative spine SBRT

J Neurosurg Spine 26:299–306, 2017

Although postoperative stereotactic body radiation therapy (SBRT) for spinal metastases is increasingly performed, few guidelines exist for this application. The purpose of this study is to develop consensus guidelines to promote safe and effective treatment for patients with spinal metastases.

METHODS Fifteen radiation oncologists and 5 neurosurgeons, representing 19 centers in 4 countries and having a collective experience of more than 1300 postoperative spine SBRT cases, completed a 19-question survey about postoperative spine SBRT practice. Responses were defined as follows: 1) consensus: selected by ≥ 75% of respondents; 2) predominant: selected by 50% of respondents or more; and 3) controversial: no single response selected by a majority of respondents.

RESULTS Consensus treatment indications included: radioresistant primary, 1–2 levels of adjacent disease, and previous radiation therapy. Contraindications included: involvement of more than 3 contiguous vertebral bodies, ASIA Grade A status (complete spinal cord injury without preservation of motor or sensory function), and postoperative Bilsky Grade 3 residual (cord compression without any CSF around the cord). For treatment planning, co-registration of the preoperative MRI and postoperative T1-weighted MRI (with or without gadolinium) and delineation of the cord on the T2-weighted MRI (and/or CT myelogram in cases of significant hardware artifact) were predominant. Consensus GTV (gross tumor volume) was the postoperative residual tumor based on MRI. Predominant CTV (clinical tumor volume) practice was to include the postoperative bed defined as the entire extent of preoperative tumor, the relevant anatomical compartment and any residual disease. Consensus was achieved with respect to not including the surgical hardware and incision in the CTV. PTV (planning tumor volume) expansion was controversial, ranging from 0 to 2 mm. The spinal cord avoidance structure was predominantly the true cord. Circumferential treatment of the epidural space and margin for paraspinal extension was controversial. Prescription doses and spinal cord tolerances based on clinical scenario, neurological compromise, and prior overlapping treatments were controversial, but reasonable ranges are presented. Fifty percent of those surveyed practiced an integrated boost to areas of residual tumor and density override for hardware within the beam path. Acceptable PTV coverage was controversial, but consensus was achieved with respect to compromising coverage to meet cord constraint and fractionation to improve coverage while meeting cord constraint.

CONCLUSIONS The consensus by spinal radiosurgery experts suggests that postoperative SBRT is indicated for radioresistant primary lesions, disease confined to 1–2 vertebral levels, and/or prior overlapping radiotherapy. The GTV is the postoperative residual tumor, and the CTV is the postoperative bed defined as the entire extent of preoperative tumor and anatomical compartment plus residual disease. Hardware and scar do not need to be included in CTV. While predominant agreement was reached about treatment planning and definition of organs at risk, future investigation will be critical in better understanding areas of controversy, including whether circumferential treatment of the epidural space is necessary, management of paraspinal extension, and the optimal dose fractionation schedules.

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Management of posterior inferior cerebellar artery aneurysms

Acta Neurochir (2017) 159:549–558

Posterior inferior cerebellar artery (PICA) aneurysms are an uncommon, heterogeneous group of aneurysms with poorer clinical outcomes compared to other intracranial aneurysms. We performed a multicenter retrospective study to analyze the outcome in a large series of patients treated with modern microsurgical and endovascular techniques.

Methods Records of 94 patients treated for PICA aneurysms between 2000 and 2015 at three large tertiary referral centers were retrospectively reviewed.

Results Eighty-three patients met inclusion criteria and of these, two died before treatment, leaving 81 treated patients (43 underwent endovascular and 38 surgical treatment). Among patients treated endovascularly, procedure-related complications occurred in four cases (11.8%). Six patients (19.4%) suffered from complications directly associated with surgery. Recurrences occurred in 0% of surgical and in 16.3% of endovascularly treated patients, requiring treatment. Patients with unruptured asymptomatic aneurysms had good outcomes. In the group of 67 ruptured aneurysms, 16 endovascularly (47.1%) and 15 surgically (48.4%) treated patients had modified Rankin scale (mRS) scores of 3–6. Of patients in poor neurological condition (Hunt & Hess (H&H) IV–V at admission), 84.6% suffered a poor clinical outcome. Fifty percent of patients with distal and 31.9% pa- tients with proximal ruptured PICA aneurysms suffered a poor neurological outcome.

Conclusions This study of PICA aneurysms demonstrates that results of both treatment modalities are comparable. However, endovascular treatment is associated with higher risks of recurrence, requiring additional treatment. Outcomes were mostly impacted by clinical state at admission.

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The new WHO 2016 classification of brain tumors

Acta Neurochir (2017) 159:403–418

The understanding of molecular alterations of tumors has severely changed the concept of classification in all fields of pathology. The availability of high-throughput technologies such as next-generation sequencing allows for a much more precise definition of tumor entities. Also in the field of brain tumors a dramatic increase of knowledge has occurred over the last years partially calling into question the purely morphologically based concepts that were used as exclusive defining criteria in the WHO 2007 classification.

Methods Review of the WHO 2016 classification of brain tumors as well as a search and review of publications in the liter- ature relevant for brain tumor classification from 2007 up to now.

Results The idea of incorporating the molecular features in classifying tumors of the central nervous system led the authors of the new WHO 2016 classification to encounter inevitable conceptual problems, particularly with respect to linking morphology to molecular alterations. As a solution they introduced the concept of a “layered diagnosis” to the classification of brain tumors that still allows at a lower level a purely morphologically based diagnosis while partially forcing the incorporation of molecular characteristics for an “integrated diagnosis” at the highest diagnostic level. In this context the broad availability of molecular assays was debated. On the one hand molecular antibodies specifically targeting mutated proteins should be available in nearly all neuropathological laboratories. On the other hand, different high-throughput assays are
accessible only in few first-world neuropathological institutions. As examples oligodendrogliomas are now primarily defined by molecular characteristics since the required assays are generally established, whereas molecular grouping of ependymomas, found to clearly outperform morphologically based tumor interpretation, was rejected from inclusion in the WHO 2016 classification because the required assays are currently only established in a small number of institutions.

Conclusion In summary, while neuropathologists have now encountered various challenges in the transitional phase from the previous WHO 2007 version to the new WHO 2016 clas- sification of brain tumors, clinical neurooncologists now face many new diagnoses allowing a clearly improved understand- ing that could offer them more effective therapeutic opportu- nities in neurooncological treatment. The new WHO 2016 classification presumably presents the highest number of modifications since the initial WHO classification of 1979 and there- by forces all professionals in the field of neurooncology to intensively understand the new concepts. This review article aims to present the basic concepts of the new WHO 2016 brain tumor classification for neurosurgeons with a focus on neurooncology.

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Comparison of clipping and coiling in elderly patients with unruptured cerebral aneurysms

J Neurosurg 126:811–818, 2017

The comparative effectiveness of the 2 treatment options—surgical clipping and endovascular coiling—for unruptured cerebral aneurysms remains an issue of debate and has not been studied in clinical trials. The authors investigated the association between treatment method for unruptured cerebral aneurysms and outcomes in elderly patients.

METHODS The authors performed a cohort study of 100% of Medicare fee-for-service claims data for elderly patients who had treatment for unruptured cerebral aneurysms between 2007 and 2012. To control for measured confounding, the authors used propensity score conditioning and inverse probability weighting with mixed effects to account for clus- tering at the level of the hospital referral region (HRR). An instrumental variable (regional rates of coiling) analysis was used to control for unmeasured confounding and to create pseudo-randomization on the treatment method.

RESULTS During the study period, 8705 patients underwent treatment for unruptured cerebral aneurysms and met the study inclusion criteria. Of these patients, 2585 (29.7%) had surgical clipping and 6120 (70.3%) had endovascular coiling. Instrumental variable analysis demonstrated no difference between coiling and clipping in 1-year postoperative mortality (OR 1.25, 95% CI 0.68–2.31) or 90-day readmission rate (OR 1.04, 95% CI 0.66–1.62). However, clipping was associ- ated with a greater likelihood of discharge to rehabilitation (OR 6.39, 95% CI 3.85–10.59) and 3.6 days longer length of stay (LOS; 95% CI 2.90–4.71). The same associations were present in propensity score–adjusted and inverse probability–weighted models.

CONCLUSIONS In a cohort of Medicare patients, there was no difference in mortality and the readmission rate between clipping and coiling of unruptured cerebral aneurysms. Clipping was associated with a higher rate of discharge to a rehabilitation facility and a longer LOS.

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Lumbar Spinal Stenosis Associated With Degenerative Lumbar Spondylolisthesis: A Systematic Review and Meta-analysis of Secondary Fusion Rates Following Open vs Minimally Invasive Decompression

Neurosurgery 80:355–367, 2017

Decompression without fusion is a treatment option in patients with lumbar spinal stenosis (LSS) associated with stable low-grade degenerative spondylolis- thesis (DS). A minimally invasive unilateral laminotomy (MIL) for “over the top” decom- pression might be a less destabilizing alternative to traditional open laminectomy (OL). OBJECTIVE: To review secondary fusion rates after open vs minimally invasive decom- pression surgery.

METHODS: We performed a literature search in Pubmed/MEDLINE using the keywords “lumbar spondylolisthesis” and “decompression surgery.” All studies that separately reported the outcome of patients with LSS+DS that were treated by OL or MIL (transmuscular or subperiosteal route)were included in our systematic review and meta-analysis. The primary end point was secondary fusion rate. Secondary end points were total reoperation rate, postoperative progression of listhetic slip, and patient satisfaction.

RESULTS: We identified 37 studies (19 with OL, 18 with MIL), with a total of 1156 patients, that were published between 1983 and 2015. The studies’evidence was mostly level 3 or 4. Secondary fusion rates were 12.8% after OL and 3.3% after MIL; the total reoperation rates were 16.3% after OL and 5.8% after MIL. In the OL cohort, 72% of the studies reported a slip progression compared to 0% in the MIL cohort, respectively. After OL, satisfactory outcome was 62.7% compared to 76% after MIL.

CONCLUSION: In patients with LSS and DS, minimally invasive decompression is associated with lower reoperation and fusion rates, less slip progression, and greater patient satisfaction than open surgery.

 

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Results of surgery in symptomatic non-hydrocephalic pineal cysts

Acta Neurochir (2017) 159:349–361

We have previously proposed that pineal cysts (PCs) may result in crowding of the pineal recess, causing symptoms due to compression of the internal cerebral veins and central venous hypertension. In the present study, we compared clinical outcome of different treatment modalities in symptomatic individuals with non-hydrocephalic PCs.

Methods The study included all patients managed surgically for non-hydrocephalic PCs in our Department of Neurosurgery over a 10-year period. We applied a questionnaire to determine occurrence of symptoms before and after surgery, which allowed the use of a grading scale for symptom severity. Magnetic resonance imaging (MRI) biomarkers indicative of central venous hypertension were assessed before and after surgery.

Results Relief of symptoms after surgery was most efficiently obtained by complete microsurgical cyst removal [n = 15; no (0/15), some (1/15) or marked (14/15) improvement], and to a lesser extent by microsurgical cyst fenestration [n = 6; no (2/6), some (4/6) or marked (0/6) improvement]. Shunt surgery was not successful [n = 6; no (5/6), some (1/6) or marked (0/6) improvement]. In all patients, the proposed MRI biomarkers gave evidence of central venous hypertension (PC grades 2–4).

Conclusions Microsurgical cyst removal provided marked symptom relief in symptomatic individuals with non-hydrocephalic PCs and MRI biomarkers of central venous hypertension. The hypothesis that PC-induced crowding of the pineal recess may compromise venous run-off and induce a central venous hypertension syndrome deserves further study.

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Can segmental mobility be increased by cervical arthroplasty?

Neurosurg Focus 42 (2):E3, 2017

Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations.

METHODS Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)–measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2–7 Cobb angle, the difference between pre- and postoperative C2–7 Cobb angle (DC2–7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and post- operative SVA (DSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (DROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up.

RESULTS A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (DROM) were -0.5° ± 6.13°. Patients with increased segmental mobility after surgery (DROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose DROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2–7 Cobb angles and SVA remained similar. The postoperative C2–7 Cobb angles, SVA, DC2–7 Cobb angles, and DSVA were not correlated to clinical outcomes after CDA.

CONCLUSIONS Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2–7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (DROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (DROM < 0°).

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Percutaneous Instrumentation Without Arthrodesis for Thoracolumbar Flexion-Distraction Injuries

Neurosurgery 80:171–179, 2017

Flexion-distraction injuries (FDI) represent 5% to 15% of traumatic thoracolumbar fractures. Treatment depends on the extent of ligamentous involvement: osseous/Magerl type B2 injuries can be managed conservatively, while ligamentous/Magerl type B1 injuries undergo stabilization with arthrodesis. Minimally invasive surgery without arthrodesis can achieve similar outcomes to open procedures. This has been studied for burst fractures; however, its role in FDI is unclear.

OBJECTIVE: To conduct a systematic review of the literature that examined minimally invasive surgery instrumentation without arthrodesis for traumatic FDI of the thora- columbar spine.

METHODS: Four electronic databases were searched, and articles were screened using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines for patients with traumatic FDI of the thoracolumbar spine treated with percutaneous techniques without arthrodesis and had postoperative follow-up.

RESULTS: Seven studies with 44 patients met inclusion criteria. There were 19 patients with osseous FDI and 25 with ligamentous FDI. When reported, patients (n = 39) were neuro- logically intact preoperatively and at follow-up. Osseous FDI patients underwent instru- mentation at 2 levels, while ligamentous injuries at approximately 4 levels. Complication rate was 2.3%. All patients had at least 6 mo of follow-up and demonstrated healing on follow-up imaging.

CONCLUSION: Percutaneous instrumentation without arthrodesis represents a low-risk intermediate between conservative management and open instrumented fusion. This “internal bracing” can be used in osseous and ligamentous FDIs. Neurologically intact patients who do not require decompression and those that may not tolerate or fail conser- vative management may be candidates. The current level of evidence cannot provide official recommendations and future studies are required to investigate long-term safety and efficacy.

 

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